"Eventually the plan is to be able to interview her when she is stable enough," Fratianni said. "We don't know when that will be."

Ava suffered several stab wounds when her mother, podiatrist Victoria Vovchik, turned on her with a weapon on Thursday at their upscale New City home, about 30 miles from Manhattan, police said. Vovchik then stabbed herself to death, they said.

Fratianni wouldn't say if a motive had been detected. She said no note had been found.

The victims were discovered by Ava's father, Kristappa Sangavaram, a New Jersey anesthesiologist. He had been alerted by Ava's school that she was absent, and he went to the home to check on her, Fratianni said.

Sangavaram and Vovchik had never been married, Fratianni said.

He called 911 to report "a possible suicide," police said. He was not being held.

Fratianni would not say exactly what kind of weapon was used in the attack.

"We have evidence we've collected at the scene but we're not able to disclose that," she said.

She said investigators were awaiting the Rockland County medical examiner's findings before announcing an official cause of death.